This invention relates generally to disc brakes and more specifically to railroad disc brake pads.
Railroad disc braking is quite common in Europe. Pads currently commercially available in Europe all conform to standards set by the UIC (Union Internationale Chemin de Fer). These pads usually feature a single organic composition friction element rigidly mounted on a steel back plate and having a series of grooves formed in the braking surface. Such composition pads have two disadvantages: difficulty in meeting performance standards during wet operation and poor survivability when subjected to severe braking conditions.
Other types of disc brake pad configurations have been developed. In one form, several large blocks of composition friction material are mounted rigidly to a steel back plate. Pads have been developed which feature several large composition friction elements mounted on a flexible carrier plate which is yieldingly attached to a steel back plate, with a layer of rubber interposed between the carrier plate and the back plate. This arrangement, shown in U.S. Pat. Nos. 2,451,326; 2,451,329 and 3,198,294, allegedly permits the several separate elements to move independently and thus better conform to a mating disc surface. In another form of this type pad, the rubber material is removed and the back plate is provided with protuberances beneath each element to permit individual pivotal movement of the elements, as shown in U.S. Pat. No. 3,297,117. These pads have proved to be unduly complex, expensive to manufacture and have not been commercially successful.
Thus, it is an object of this invention to provide a disc brake pad having good wet performance and improved survivability during severe braking conditions.